File: Employee.java
import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.IdClass; @Entity @IdClass(EmployeePK.class) public class Employee implements java.io.Serializable { private String firstName; @Id private String lastName; @Id private long ssn; public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public long getSsn() { return ssn; } public void setSsn(long ssn) { this.ssn = ssn; } } class EmployeePK implements java.io.Serializable { private String lastName; private long ssn; public EmployeePK() { } public EmployeePK(String lastName, long ssn) { this.lastName = lastName; this.ssn = ssn; } public String getLastName() { return this.lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public long getSsn() { return ssn; } public void setSsn(long ssn) { this.ssn = ssn; } public boolean equals(Object obj) { if (obj == this) return true; if (!(obj instanceof EmployeePK)) return false; EmployeePK pk = (EmployeePK) obj; if (!lastName.equals(pk.lastName)) return false; if (ssn != pk.ssn) return false; return true; } public int hashCode() { return lastName.hashCode() + (int) ssn; } }
File: Helper.java
import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class Helper { public static void checkData() throws Exception { Class.forName("org.hsqldb.jdbcDriver"); Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", ""); Statement st = conn.createStatement(); ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String[] { "TABLE" }); while (mrs.next()) { String tableName = mrs.getString(3); System.out.println("\n\n\n\nTable Name: "+ tableName); ResultSet rs = st.executeQuery("select * from " + tableName); ResultSetMetaData metadata = rs.getMetaData(); while (rs.next()) { System.out.println(" Row:"); for (int i = 0; i < metadata.getColumnCount(); i++) { System.out.println(" Column Name: "+ metadata.getColumnLabel(i + 1)+ ", "); System.out.println(" Column Type: "+ metadata.getColumnTypeName(i + 1)+ ": "); Object value = rs.getObject(i + 1); System.out.println(" Column Value: "+value+"\n"); } } } } }
File: Main.java
import java.util.List; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import javax.persistence.Query; public class Main { static EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService"); static EntityManager em = emf.createEntityManager(); public static void main(String[] a) throws Exception { em.getTransaction().begin(); em.getTransaction().commit(); em.close(); emf.close(); Helper.checkData(); } }
File: persistence.xml
<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence" version="1.0"> <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL"> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/> <property name="hibernate.connection.username" value="sa"/> <property name="hibernate.connection.password" value=""/> <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/> </properties> </persistence-unit> </persistence>
22.19.Primary Key | ||||
22.19.1. | Use UUID As Primary Key | ![]() | ||
22.19.2. | Use Current Milisecond As ID | ![]() | ||
22.19.3. | Set Primary Key Join Column For Entities In Hierarchy | ![]() | ||
22.19.4. | Set ID By Yourself | ![]() | ||
22.19.5. | Not Nullable ID | ![]() | ||
22.19.6. | ID Entity With Hash Code And Equals | ![]() | ||
22.19.7. | Id Containing Relationship | ![]() | ||
22.19.8. | Embedded Compound Primary Key | ![]() | ||
22.19.9. | Define Extra Class For Compound Key | ![]() |